Meaning of CMOS and typical device mode: “CMOS” expands to “complementary metal-oxide-semiconductor,” and in mainstream logic processes the field-effect transistors are normally enhancement-mode devices. Is this statement correct?

Difficulty: Easy

Correct Answer: Correct

Explanation:


Introduction / Context:
CMOS stands for “complementary metal-oxide-semiconductor,” referring to the complementary use of p-channel and n-channel MOSFETs. Understanding the naming and the common operating mode of transistors in digital CMOS is fundamental to logic design.



Given Data / Assumptions:

  • Complementary means paired pMOS and nMOS devices form logic functions (for example, CMOS inverters, NAND, NOR).
  • Standard digital CMOS uses enhancement-mode MOSFETs whose channels form when a gate voltage exceeds a threshold in the appropriate polarity.
  • Depletion-mode devices exist but are uncommon in standard-cell digital logic paths.


Concept / Approach:
Digital CMOS relies on enhancement-mode devices so that, at steady state, either the pull-up or pull-down network is off, minimizing static current. The phraseology in the question is slightly pluralized, but the technical substance—expansion of CMOS and enhancement-mode usage—is correct.



Step-by-Step Solution:

Expand acronym: CMOS = complementary metal-oxide-semiconductor.Identify device mode: enhancement-mode MOSFETs for both pMOS and nMOS transistors.Relate to logic behavior: complementary networks minimize static current.Conclude the statement is correct.


Verification / Alternative check:
Semiconductor texts and process overviews confirm enhancement-mode devices in mainstream CMOS logic libraries.



Why Other Options Are Wrong:

Incorrect: Conflicts with standard terminology and device usage.Correct only for pMOS / only below 3.3 V: Enhancement-mode usage is not limited to a single polarity or narrow voltage range.


Common Pitfalls:
Confusing analog specialty processes (where depletion loads may appear) with mainstream digital logic; misremembering the expansion of CMOS.


Final Answer:
Correct

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